The proposed research is designed to clarify the relationship between identifiable biochemical aberrations responsible for abnormal polymorphonuclear leukocyte function, the wound events, and systemic changes seen in thermally injured patients. The studies will be focused: 1) to identify mechanisms of decreased oxidative functions and the status of reactive oxygen species in intact leukocytes; 2) to relate these oxidative responses to factors in burn serum/plasma or would fluid; 3) to isolate and characterize the sera and fluid factor(s) which affect oxidative processes and therefore bacterial kill; 4) to correlate the domonstrated functional O2 abnormalities with structural changes by electron microscopy and histochemical determinations to characterize circulating and wound fluid cell populations; and 5) to attempt to relate wound environment (cellular and fluid) observations to the types of organisms colonizing burn wounds. Understanding of the biochemical events in PMN function and their relation to bacterial colonization is essential before appropriate local or systemic therapeutic interventions can be contemplated.